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Astronomy

1

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Universe Cycle - Solar System

1404 2013 Exam

Chapter 7Chapter 7

Meteorology (Chapter 6 )

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Chapter 6Chapter 6

Universe Cycle - Solar System

Meteorology

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GosmolgyGosmolgy the branch of astronomy that deals with the general structure and evolution of the universe GosmolgyGosmolgy the branch of astronomy that deals with the general structure and evolution of the universe

The Milky WayMilky Way is the galaxy that contains the Earth

GalaxyGalaxy A system of millions or billions of stars together with gas and dust held together by gravitational attraction

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Universe Cycle - Solar System

bull The universe is commonly defined as the totality of everything

that exists including all physical matter and energy the

planets stars galaxies and the contents of intergalactic

space

Meteorology (Chapter 6 )

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Contents

bull The Solar Systembull Starsbull Solar Systems Galaxies amp the Universebull Comets asteroids and meteoroids bull History of the Universebull Future of the Universe

Meteorology (Chapter 6 )

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The Solar System

In the Universethe Solar System is our homelandand the Earth is our hometown

What is the Solar System

Meteorology (Chapter 7 )

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The Solar System

The Solar System consists of

bull the sun in its centrebull nine planets

circling around the sunbull moonsbull asteroidsbull and comets

Meteorology (Chapter 6 )

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The Solar System

How did the Solar System evolve

bull Scientists are quite sure that in the beginning of our Solar System there was a huge disc of dirt rocks gas ice etc

bull In the middle of this disc the Sun formed itself and began to glow

bull In some distances from the centre the planets emerged from these rings of dirt rocks and gas

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The Solar System

How large is our Solar System

bull The orbit on which Pluto (the farthest planet) circles the sun has an average diameter of 5910000000 km (Plutolsquos orbit is rather non-circular)

bull The sun itself the largest object in our Solar System has a diameter of 1392520 km

Meteorology (Chapter 6 )

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The Solar System

Meteorology (Chapter 6 )

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Planets

bull Rocky planets 1048697 Formed below the frost line (asymp 3 AU) 1048697 Rich in metal and silicates Small sizes 1048697 Unable to retain H2 or He Thin atmospheresbull Gaseous planets 1048697 Formed beyond the frost line 1048697 Condensation of volatiles Large sizes 1048697 Large atmospheres of H2 and He

Meteorology (Chapter 6 )

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The Planets

Mercury is the planet that is closest to our Sun Pluto is the farthest Remember the order of the planets like this

My Very Educated Mother Just Showed Us Nine Planets

which meansMercury Venus Earth Mars Jupiter Saturn

Uranus Neptun Pluto

Meteorology (Chapter 6 )

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Stars

bull Stars are burning balls of gas eg our Sun

bull Stars give out light

bull This light reflects off planets so we can see them

bull Planets are much smaller than starshellip but they seem much bigger as they are much closer

bull The 9 planets orbit the sun Earth orbits the Sun once a year

Meteorology (Chapter 6 )

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Solar Systems Galaxies amp the UniverseOur Sun is one of

millions of stars that orbit the centre of the

Universe

The Milky Way is one of more than a billion galaxies in the Universe

The Universe is expandingMeteorology (Chapter 6 )

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Solar Systems Galaxies amp the Universe

Meteorology (Chapter 6 )

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Small Bodies

There are other smaller object that orbit the Sun including asteroids comets meteoroids and dwarf planets bullAsteroids (also called minor planets) are rocky or metallic objects most of which orbit the Sun in the asteroid belt between Mars and Jupiter

bullComets are small icy bodies that orbit the sun They have very long tails

bullMeteoroids are small bodies that travel through space They are stony andor metallic and are smaller than asteroids Most are very tiny

Meteorology (Chapter 6 )

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Cometsbull Comets appear every few yearsbull Comets have highly elliptical orbits around the Sun

bull Comets are visible when they are close to the Sunbull A cometrsquos orbit is fastest near the Sun due to the Sunrsquos gravity It

slows as it moves further away from the Sun

Tail is made of ice and rock

Tail is pushed away from sun by solar pressure

Meteorology (Chapter 6 )

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History of the Universe

Big Bang Theory

bull Universe was compressed and exploded ndash Big Bang

bull Occurred 15 billion years ago

bull Estimated by current rate of expansion

bull Expansion is slowing due to gravity

Meteorology (Chapter 6 )

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Summary

bull Solar system ndash 9 planets amp 1 star

bull Stars emit light planets reflect this light

bull Solar systems are in galaxies which are in the Universe

bull Comets (rock and ice) have long elliptical orbits around Sun

bull Life cycle of stars ndash differs for massive amp small stars

bull History of the Universe ndash Big Bang

Meteorology (Chapter 6 )

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The terminating of part 1

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Planets

bull Rocky planets 1048697 Formed below the frost line (asymp 3 AU) 1048697 Rich in metal and silicates Small sizes 1048697 Unable to retain H2 or He Thin atmospheresbull Gaseous planets 1048697 Formed beyond the frost line 1048697 Condensation of volatiles Large sizes 1048697 Large atmospheres of H2 and He

Meteorology (Chapter 6 )

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The Planets

Mercury is the planet that is closest to our Sun Pluto is the farthest Remember the order of the planets like this

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Mercury

What are Mercurylsquos features

bull second smallest planetbull nearest to the sunbull one Mercury-year is a quarter Earth-yearbull Mercury is very difficult to be spotted with the naked

eyebull Mercury has no moons

Meteorology (Chapter 6 )

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Venus

What are Venuslsquo features

bull it is a medium sized planet 25 times as large as Mercury

bull second nearest to the sunbull Venus is very well visible to the naked eye always

close to the sun before sunrise or after sunsetbull Venus has no moons

Meteorology (Chapter 6 )

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Earth

What are Earthlsquos features

bull it is a medium sized planet a bit larger than Venusbull (probably) the only planet with liquid water in our

Solar Systembull the Earth has one moonbull (probably) the only planet with intelligent life in our

Solar System

Meteorology (Chapter 6 )

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Mars

What are Marslsquo features

bull it is a small sized planet half as large as Earthbull Mars is well visible to the naked eyebull Mars has two moons Phobos and Deimosbull Mars has been visited by robotic vehicles

Pathfinder Spirit and Opportunitybull the question for (former) life on Mars is still unsolved

Meteorology (Chapter 6 )

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Jupiter

What are Jupiterlsquos features

bull it is the largest planet of the Solar Systemmore than 1300 Earths could fit inside

bull Jupiter is well visible to the naked eyebull The Great Red Spot on its surface is a giant storm as

wide as three Earthsbull Jupiter has 63 moons (the largest are Io Callisto

Ganymede and Europa)

Meteorology (Chapter 6 )

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Saturn

What are Saturnlsquos features

bull it is the second-largest planet of the Solar System only a bit smaller than Jupiter

bull Saturn is well visible to the naked eyebull the famous rings can be seen with small telescopesbull Saturn has at least 34 moons (recently a probe

landed on Jupiterlsquos moon Titan)

Meteorology (Chapter 6 )

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Uranus

What are Uranuslsquo features

bull it is medium sized planet of the Solar Systembull it is quite far away but still can be spotted with small

telescopesbull like Saturn Uranus has a system of ringsbull Saturn has at least 27 moons

Meteorology (Chapter 6 )

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Neptune

What are Neptunelsquos features

bull it is medium sized planet of the Solar System only a little bit smaller than Uranus

bull it is quite far away but still can be spotted with small telescopes

bull Neptune has four rings and at least 13 moons

Meteorology (Chapter 6 )

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Pluto

What are Plutolsquos features

bull it is the smallest planet of our Solar Systembull Since Pluto is far away and so small you need a

medium-sized professional telescope or a good amateur telescope to spot it

bull Noone knows what Pluto looks like ndash itlsquos too far away and too small The picture in the background is an artistlsquos rendition

bull Pluto has one moon Charon

Meteorology (Chapter 6 )

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Moons

What are moons

bull Moons are like little planets that encircle the real planets

bull Usually they are much smaller than planetsbull Planets can have no moons (like Mercury and Venus)

one moon (like Earth) or up to a very large number of moons (eg 63 for Jupiter)

Meteorology (Chapter 6 )

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Moons

Phobos and Deimos

bull Phobos and Deimos are Marslsquo companions Phobos means ldquofearldquo Deimos means ldquopanicldquo Mars itself has been named for the Roman God of War

bull They are quite small (lt15km) and look rather like potatoes than like moons

Meteorology (Chapter 6 )

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Moons

Io Callisto Ganymed and Europa

bull These four moons are the biggest moons of Jupiter They can be seen with small telescopes or even with binoculars

Europa

Io

Meteorology (Chapter 6 )

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Planets of other stars

Are there more planets in the Universe (except for the ones in the Solar System)

bull Yes there are other planets so-called extra-solar planets

But it is very difficult to spot them since they are far far away

Meteorology (Chapter 6 )

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Planets of other stars

How can planets of other stars be spotted

There are two main ways that astronomers search for these planets

bull If you observe a star very accurately with special instruments you may be able to measure a slight ldquowobbleldquo This can indicate a planet

bull If you can observe many stars after night you may sometimes see one get slightly fainter for a little while This happens if a planet passes between us and the star ndash like a mini-eclipse

Meteorology (Chapter 6 )

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More InformationSkyWatch linksbull Views of the Solar Systembull The Nine Planetsbull StarChild

Celestia Exploration Activityhttplearnarcnasagovplanets

Solar System Explorationhttpsolarsystemnasagovplanets

Welcome to the Planetshttppdsjplnasagovplanets

Meteorology (Chapter 6 )

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The terminating of part 2

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Discovering the atmosphere on different planets

An atmosphere is the layer of gases that envelop a planet On the Earth it is this envelope

that allows organisms to live Atmospheric ozone protects us from ultraviolet radiation CO2

and other gases trap heat and keep the surface warm enough for life to thrive Oxygen has

allowed life to evolve

Each of the planets has a different atmosphere although there are clear similarities between

the atmospheres of the four terrestrial planets and the four gas giant planets The terrestrial

planets are rich in heavier gases and gaseous compounds such as carbon dioxide

nitrogen oxygen ozone and argon In contrast the gas giant atmospheres are composed

mostly of hydrogen and helium

The atmospheres of at least the inner planets have evolved since they formed This is

clearest for the Earth The Earthrsquos original atmosphere was probably similar to Venus in

composition consisting of carbon dioxide and nitrogen The evolution of photosynthesis

converted carbon dioxide in the Earthrsquos atmosphere to oxygen increasing the amount of O2

in it from an initial 001 to its current 22 level

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Astronomical unit

Definition An Astronomical Unit is approximately the mean

distance between the Earth and the Sun It is a derived constant

and used to indicate distances within the solar system

1 AU = 149597870691 kilometers

Meteorology (Chapter 6 )

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NASAbull The (National Aeronautics and Space

Administration) is an Executive Branch agency of

the United States government responsible for the

nations civilian space program and aeronautics and

aerospace research Since February 2006 NASAs

self-described mission statement is to pioneer the

future in space exploration scientific discovery and

aeronautics research

Meteorology (Chapter 6 )

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Atmospheres of the rocky planets

Meteorology (Chapter 6 )

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Atmospheres of Uranus and NeptuneAtmospheres of Uranus and Neptune

Meteorology (Chapter 6 )

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HomeworkHomework